CVE-2022-38546Network attack vector

DNS tunneling and amplification via open resolver

Published Dec 21, 2022 · Updated Apr 15, 2025

Improper access control in Zyxel NBG7510 firmware 1.00(ABZY.2)C0 and earlier allows remote attackers to abuse its DNS resolver. In AP mode, the DNS configuration exposes an open resolver that accepts unauthenticated queries instead of restricting resolution to authorized clients. Reachability requires AP mode and enables DNS tunneling or amplification against third parties.

CVSS severity5.3
Medium
EPSS probability0.62%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Improper access control in Zyxel NBG7510 firmware 1.00(ABZY.2)C0 and earlier allows remote attackers to abuse its DNS resolver. In AP mode, the DNS configuration exposes an open resolver that accepts unauthenticated queries instead of restricting resolution to authorized clients. Reachability requires AP mode and enables DNS tunneling or amplification against third parties.

The record

CVE
CVE-2022-38546
Published
Dec 21, 2022
Updated
Apr 15, 2025
Vendor
Zyxel Networks
Product
NBG7510 firmware
Classifications
CWE-284, T1498.002, T1071.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 21, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 15, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< V1.00(ABZY.3)C0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Zyxel Networks · NBG7510 firmwareversion=< V1.00(ABZY.3)C0

Published CVSS scores

5.3Zyxel CorporationCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-284Improper Access Control
T1498.002Network Denial of Service: Reflection Amplification
T1071.004Application Layer Protocol: DNS

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo